Disc brakes are commonly used in various applications such as in vehicles for slowing or stopping the vehicle. Disc brakes are also connected to the output shaft of a prime mover, such an internal combustion engine, for measuring the output power as in a dynamometer. Disc brakes are also increasingly being used in high energy storage devices employing a rotating flywheel for controlling the speed of rotation of the flywheel. In these types of applications, the disc brake engages a moving rotor for controlling the speed, or even stopping, the rotor.
In a high speed flywheel energy storage device, the flywheel rotor is often magnetically suspended and operates at very high speeds. These types of flywheel rotors typically have a composite composition and are the product of extensive design and development efforts and are expensive. Stopping a rotor such as for an emergency requires the application of a large torque on the rotor resulting in the generation of large amounts of heat which can damage or destroy the rotor and other energy storage device components. An emergency may arise because of a loss of cryostat cooling, a loss of vacuum within which the flywheel rotor operates, or the loss of the energy storage device's computer control system. In any of these cases, it is of the utmost importance to safely and quickly bring the flywheel rotor to a complete stop so as to avoid damaging the system or injuring operating personnel. In addition, for safety and operating purposes, it is essential that the rotor be precisely located vertically and laterally within the energy storage device particularly during initiation of the operation of the flywheel energy storage device using magnetic bearings. To date, the inability to safely stop a high speed, high energy magnetically suspended flywheel rotor in an energy storage device and to consistently and precisely position the rotor within the energy storage device have limited the use of these types of devices in commercial environments and applications.
One embodiment of the present invention addresses the aforementioned limitations of the prior art by providing a safe and efficient braking system for a high speed, high load rotor magnetically suspended in a flywheel energy storage device and also provides the capability for consistently and accurately positioning the rotor within the energy storage device particularly at initiation of operation of the device.